Five things to know why this spring's Mississippi River flooding is particularly bad

Spring flooding on the upper Mississippi River has reached nearly historic levels this year, the result of overwhelming — and quick — snowmelt from Minnesota and Wisconsin.

The water is drenching fields and parks, impeding transportation and creeping into homes and businesses. Communities have come together to sandbag and wait out the worst of it until the river begins to return to its banks, and they can start cleaning up the damage left behind.

Here are five things to know about what's unfolding.

More: As heavy, wet snow melts, upper Mississippi River floods to near record levels

Floodwaters are among the highest levels on record

In the spring 1965, the upper river flooded to its highest level ever recorded, causing $225 million in property damage. The second-highest floodwaters, at least in many locations, were recorded in spring 2001.

Now, in La Crosse and Prairie du Chien, the river has reached its third-highest level ever. Several other locations along the river recorded levels that are in the all-time top five, according to Jordan Wendt, service hydrologist at the National Weather Service's La Crosse office.

It's a result of all the snow we got during the winter

You surely haven't forgotten how winter unfolded across Wisconsin and Minnesota, and then dropped what seemed like weekly wet, heaving snowstorms in the last few months.

The river floods every year due to snowmelt, but this year, an abundance of heavy snow held an extreme amount of water. Then, when the region experienced a string of 70-degree days in mid-April, that snow melted and water began pouring into tributaries on its way to the Mississippi.

Forecasters initially feared that the floodwaters could be worse than the 2001 levels or even approach 1965 levels, Wendt said. But the soil, still on the drier side from last fall's drought, soaked up water for the first three days of the melt, taking the edge off before it started running toward the river and flooding.

More: Heavy, wet snow in upper Wisconsin, Minnesota raises risk of serious Mississippi River flooding

The flooding is shutting down roads and halting river barges

Several locks and dams on the upper river are closed due to high water, meaning barges can't move upriver and downriver with goods that need to be delivered.

Patrick Moes, deputy public affairs chief for the U.S. Army Corps of Engineers' St. Paul District, said some locks are closed because the water levels are higher than the lock itself, which boats use to pass through different sections of the river. That's the case in Alma. In other places, swirling currents were pushing barges too close to the dams.

As of late in the week, the Great River Road, also known as Wisconsin Hwy. 35, was closed in Fountain City. A bridge that connects Lansing, Iowa, to the De Soto area in Wisconsin had been shut down so officials could inspect the integrity of the attached dike. (The same state highway also was because a train derailed in the area Thursday, sending two cars into the river. It's unclear if high water had any impact on the incident.)

More: Train derails in Wisconsin, south of De Soto in Crawford County along Mississippi River

Far southwestern Wisconsin and northeast Iowa were hit hardest

Prairie du Chien and McGregor, Iowa, which sit near the spot where the Wisconsin River joins up to the Mississippi, were hit particularly hard during this spring's flooding.

So much water was rushing in from the Wisconsin River that it was creating a "backwater effect," Wendt said — essentially forming a small lake where the water waited until it could flow down the Mississippi.

The river will start receding over the next week

The river has crested in many upriver communities and the floodwaters will slowly begin to recede. Then cleanup will begin, clearing away mud and debris washed ashore by the swollen river and inspecting properties that were inundated for mold.

Nate Melby is the fire chief in the Town of Campbell on low-lying French Island, near the city of La Crosse, where floodwaters infiltrated some homes.

"On the way down it takes forever," he said, "because you didn't think about that part."

Madeline Heim is a Report for America corps reporter who writes about environmental issues in the Mississippi River watershed and across Wisconsin. Contact her at 920-996-7266 or mheim@gannett.com.

This article originally appeared on Milwaukee Journal Sentinel: Mississippi river floods: 5 things to know about why this year is bad